Poizner was touring San Diego's stretch of the border Monday for the first time as an official candidate and -- he said -- the second time in a year.

Whitman's campaign scoffs at Poizner's commitment to tackling the problem.

“This is another example of Steve Poizner using an issue that he has no interest in addressing but for pure self-interest and political gain," said U.S. Rep. Darrell Issa (R-Vista), a Whitman campaign co-chair, in a statement. "His priority is not addressing illegal immigration, it’s getting elected."

Nonetheless, Poizner has been working fast to shape the issue into what may be the the boldest line in the sand between him and Whitman.l He backs Arizona's controversial new law; Whitman doesn't. So he's rolling the dice on how well it plays with GOP voters in this state.

Poizner spent about three hours with Customs and Border Patrol agents before regaling reporters with his suggestions for curbing illegal immigration.

At a news conference on the pedestrian overcrossing at the San Ysidro Port of Entry, with Tijuana behind him, Poizner said that walls and fences serve as less of a deterrent to illegal immigration than turning off what he called the economic "magnets" of benefits and jobs. It's a theme that runs through his latest campaign commercial, bashing Whitman.

Poizner said Monday that he wants to end taxpayer-funded benefits to illegal immigrants and revoke the business licenses of companies that violate federal law when they hire illegal immigrants.

"If the legislature blocks these reforms -- turning off these magnets -- then I will take a ballot initiative directly to the voters," Poizner said. "We'll fine-tune it to make sure it will withstand Constitutional scrutiny, and we'll let the voters implement those changes if the legislature won't."

Poizner also vowed to send California National Guard troops to the border to serve in whatever capacity federal officials think best in backing up Border Patrol agents.

"They need the extra manpower, they need more spotters, they need the horsepower," Poizner said. "They told me today that they would welcome extra manpower to do their job at the border."

Since the Arizona law was signed last month, polls show that Poizner is closing to within a single-digit margin of Whitman with four weeks left before the June 8 primary.

This, from Team Whitman: "As someone who has spent years working on border issues, I find it inconceivable that Mr. Poizner has run two political campaigns without even including the words ‘illegal immigration’ in his previous policy platforms," Issa said in a statement released by the Whitman campaign shortly after Poizner's border tour.

"Not until the issue has surfaced in a larger national debate, 29 days before the GOP primary election, has he decided to engage on this issue ... why has it taken 602 days since declaring his ambitions for governor for him to even show up to survey the problem as a candidate?"